(1) Field of the Invention
The invention relates to the fabrication of integrated circuit devices, and more particularly, to a method to prevent backside TiN contamination for reflective product in which a layer of TiN is applied as backside material.
(2) Description of the Prior Art
Conventional methods of creating complex packages comprising semiconductor devices use semiconductor substrates over the surface of which layers of conductive interconnect traces are created, which are typically separated by layers of dielectric. The art of creating packaged semiconductor devices frequently provides for packaging semiconductor devices that are created with the purpose of processing and/or storing of digital data. Other semiconductor packages are based on packaging semiconductor storage and processing devices in addition to providing the ability to provide processing capability of on optical nature. The latter is frequently combined with processing capabilities, which are incorporated by providing discrete components that are created using semiconductor technology disciplines while resembling the electrical performance characteristics of conventionally used discrete electrical components. Examples of such semiconductor packages are the creation of solar cell based optical electronic devices, image array optical devices including sensor and display image array devices, which further comprise the familiar flat panel display image arrays and the like. These and other devices that are created using semiconductor technology have found wide application in numerous by now familiar consumer products such as the application of sensor array devices being used in digital cameras while display image array devices are frequently used as the basis for visual interface elements for mobile computers.
These new and increasingly more complex devices and device packages require control and mastery of seemingly diverse but in fact closely cooperative technologies and disciplines such as most notably a detailed knowledge of optical properties of materials and the combination of such materials with conventional although rapidly developing semiconductor materials and processing conventions. As an example can be cited the problem of optical stability that is frequently encountered in the creation of image array devices.
One of the materials that is frequently used for the creation of complex semiconductor devices and packages is glass. As an example of the application of glass in the creation of a semiconductor related component can be cited the creation of a half-tone shift mask. For the substrate of a half-tone shift mask most typically is used quartz whereby however glass and sapphire can also be used for this purpose. For half-tone shift masks the conventional shifter material is MoSiON. The standard mask comprises a substrate on the surface of which a patterned layer of opaque material is created. Typically used for the opaque material is chromium that has been deposited over the quartz substrate to a thickness of about 1,000 Angstrom. Alternate opaque materials for the creation of the patterned layer on the surface of a photolithographic mask are nickel and aluminum while for more sophisticated masks such as halftone phase shift masks MoSiON is used as the phase shifter material.
Glass in addition is frequently used as part of a compound layer of material such as creating a passivation layer, which conventionally is created using silicon nitride but may also be created using phosphosilicate glass or a layer of phosphosilicate glass over a layer of silicon oxide. Numerous other examples can be cited in which glass is part of a compound layer of semiconductor material such as the stiffener portion of a carrier substrate, which is typically composed of a fire retardant epoxy-glass cloth laminate, Fluorine doped Silicon dioxide Glass (FSG), boro-phosphate-silicate-glass (BPSG), phospho-silicate-glass (PSG), boro-silicate-glass (BSG) and the like.
The invention addresses concerns that are raised in using a glass panel for the creation of a complex semiconductor package. Glass is subject to scratch during the creation of a semiconductor package, which has a detrimental effect on the performance characteristics of the glass panel. It may for instance be required that light passes through the glass panel in an undistorted manner and without causing undesired optical reflections. It is therefore required that the surfaces of the glass panel are protected, to provide this protection of the glass surface a layer of TiN is typically deposited over the protected surfaces. Processing tools that are used to process the glass substrate after the protective and exposed layer of TiN has been deposited must be thoroughly cleaned in order to prevent contamination by TiN residue in subsequent processing steps for which these tools are applied. This is a time-consuming and therefore expensive operation. The invention provides a method whereby the need for post-processing clean of the TiN processing tool is eliminated.
U.S. Pat. No. 6,010,923 (Jinno) shows a protective layer over the front side of a glass substrate.
U.S. Pat. No. 5,731,243 (Peng et al.) shows a protective layer over the front side of a substrate during a backside grind.
U.S. Pat. No. 6,171,883 (Fan et al.) shows an image array on a glass substrate.
A principle objective of the invention is to prevent TiN contamination after a surface of a glass panel has been covered with a protective layer of TiN.
In accordance with the objectives of the invention a new method is provided for the creation of a protective layer over a glass surface. The glass panel has a first and a second surface, the first embodiment of the invention provides a protective layer of TiN over the first surface of the glass panel, the second embodiment of the invention provides a protective layer of TiN over the second surface of the glass panel.
Under a first embodiment of the invention, the second surface of the glass panel is first coated with a layer of TiN, which forms the protective layer of semiconductor material. A first layer of amorphous silicon (Axe2x80x94Si) is then deposited over the second surface of the glass panel. A second layer of amorphous silicon (Axe2x80x94Si) is then deposited over the layer of TiN that has been deposited over the first surface of the glass panel. A layer of photoresist is next deposited over the surface of the second layer of Axe2x80x94Si. The first layer of Axe2x80x94Si is removed from the second surface of the glass panel. The layer of photoresist, which has been used for the protection of the second layer of Axe2x80x94Si and the layer of TiN over the first surface of the glass panel, is then removed leaving in place a protective coating of TiN and the second layer of Axe2x80x94Si over the first surface of the glass panel.
Under a second embodiment of the invention, the first and the second surface of the glass panel are first coated with a first and a second layer of TiN respectively of which the second layer of TiN will form the protective layer of semiconductor material. A layer of amorphous silicon (Axe2x80x94Si) is then deposited over the second layer of TiN on the second surface of the glass panel. A layer of photoresist is deposited over the layer of Axe2x80x94Si. The first layer of TiN on the first surface of the glass panel is removed. The layer of photoresist, which has been used for the protection of the layer of Axe2x80x94Si and the second layer of TiN over the second surface of the glass panel, is then removed leaving in place a protective coating of the second layer of TiN and Axe2x80x94Si over the second surface of the glass panel.
From the highlighted processing sequence it is clear that the protective layer of TiN is now covered with a layer of Axe2x80x94Si, thus preventing contamination of processing tools that are used to process the glass panel with the objective of providing a protective layer of TiN over the surface thereof.